Herein, we rationally designed and fabricated the visible-light-driven Cu(OH)2/Cu2O/C3N4 photocatalyst with stable and highly efficient novel all-solid Z-scheme photocatalytic performance. It was observed that selectively fabrication of Cu(OH)2 nanoclusters on the surface of Cu2O as well as the in-situ formation of elemental Cu at the interface of Cu2O/C3N4 effectively enhanced the photoactivity of the Cu(OH)2/Cu2O/C3N4 (622 μmol H2/h/g) compared to pure C3N4 nanosheets (6 μmol H2/h/g), bare Cu2O (21 μmol H2/h/g) and even Cu2O–C3N4 heterostructure (54 μmol H2/h/g) by 103, 30, and 11.5 times, respectively. Based on the BET, DRS, PL, and electrochemical analyses, the superior performance of Cu(OH)2/Cu2O/C3N4 was proved to be mainly attributed to efficient charge carrier separation as well as high surface area of C3N4 nanosheets, noticeable visible-light response of Cu2O and SPR effect of elemental Cu. Additionally, radical species trapping was applied to more deeply study the charge carrier transfer behavior of the samples. This confirmed charge separation of Cu(OH)2/Cu2O/C3N4 followed the Z-scheme mechanism where interlayer elemental Cu as non-precious electron mediator and Cu(OH)2 nanoclusters as electron sink and noble-metal-free cocatalyst synergistically played a key role in accelerating charge carrier transfer and retarding electron-hole recombination. The current study is anticipated to open a new route for the rational design of Cu2O-based Z-scheme photocatalytic systems while taking the advantages of integrative adopting of Cu-based electron mediator and cocatalyst.

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